Question 1

A population age structure diagram in which the birthrate is high and the population is mainly young would be best represented by a graph with a(n)

Accepted Answer

A pyramid shape represents a population with a high birthrate and a mainly young population. The wider base of the pyramid indicates a larger number of young individuals, while the tapering top represents a smaller number of older individuals.

Question 2

In nature,animals tend to be either an opportunistic or equilibrium species or somewhere along an intermediate point between the two.Why aren't there animals in nature that are both big,fierce,and highly reproductive so they leave many offspring?

Accepted Answer

Energy is a limited resource in nature, and there is a trade-off between investing energy into growth and reproduction. Large animals require more energy to grow and maintain their size, leaving less energy available for reproduction. On the other hand, smaller animals have less energy to invest in growth but can allocate more energy towards producing many offspring. Therefore, an animal cannot be both big and highly reproductive because it is not possible to spend the limited energy resources on both strategies simultaneously.

Question 3

Overall,the most scientifically correct viewpoint toward predators is

Accepted Answer

Predators play an important role in keeping prey populations in check, which helps prevent overexploitation of limited food resources. This ultimately benefits the entire ecosystem by allowing for healthier and more sustainable populations of both predators and prey. Eliminating predators can have negative consequences on the overall health and balance of the ecosystem.

Question 4

Which of the following is correct when describing a predator-prey cycle?

Accepted Answer

A decline in the number of prey causes a decline in the number of predators because the predators have less food available, which leads to decreased reproduction and survival rates. As predator numbers decline, the prey population will have less predation pressure, allowing it to recover. This, in turn, will lead to an increase in the predator population, starting the cycle anew.

Question 5

The outbreak of a disease,such as the bubonic plague,that kills large numbers of people in a city is an example of

Accepted Answer

A disease outbreak is an example of a density-dependent factor because its effects are stronger in areas with higher population densities. As more people are present, there is an increased chance of transmission and thus more individuals may be affected.

Question 6

Which is NOT a density-dependent factor?

Accepted Answer

Density-dependent factors are factors that become more significant as the population density increases. Food supply, shelter or nest space, disease, and predators are all examples of density-dependent factors because they can limit the growth or survival of a population as it becomes more crowded. Weather, on the other hand, is a density-independent factor because it affects the population regardless of its size or density.

Question 7

Which of the following is NOT an anti-predator defense mechanism?

Accepted Answer

Brightly colored fruit and flowers are more likely to attract pollinators rather than repel predators, making it not an anti-predator defense mechanism.

Question 8

Similar species occupying slightly different niches in the same community is shown by

Accepted Answer

Competition between two species of barnacles in Scotland, resulting in one living in the intertidal zone and the other living below this zone, is a classic example of similar species occupying slightly different niches in the same community. These species have evolved to exploit different parts of the rocky shore, allowing them to coexist and reduce competition for resources.

Question 9

There are two organisms with overlapping ranges and filling a similar niche.We find that where their niches overlap,there is twice the competition for resources.This leads to

Accepted Answer

The increased competition for resources in the overlapping niche indicates that the organisms are in direct competition with each other. This can lead to competitive exclusion, where one species outcompetes the other and fills the niche, leading to the extinction or relocation of the other species.

Question 10

In large natural ecosystems,competition between two species over time will usually result in

Accepted Answer

In order to avoid direct competition, each species will occupy a slightly different niche or habitat within the ecosystem. This allows for the coexistence of both species over a long period of time.

Question 11

A population age structure diagram in which the birthrate is less than the death rate and the post-reproductive group is the largest would be best represented by a graph with a(n)

Accepted Answer

An urn shape indicates a population with a declining birthrate, a larger post-reproductive group, and a smaller base, suggesting a shrinking population.

Question 12

Farmers sprayed leechi trees to suppress populations of scale insects.This also killed the populations of a predatory lacewing that controlled the numbers of scales.Soon the spraying did no good,and the damage to the leechi from the scales was greater than before spraying had occurred.Few predatory lacewings existed in the trees now because

Accepted Answer

The scale insect, being an opportunistic species, can quickly adapt and develop resistance due to its high reproductive rate, while the predatory lacewing, being an equilibrium species, reproduces more slowly and takes longer to develop resistance.

Question 13

Several species of grain beetles can live on dry meal,obtaining water mostly as metabolic water.Many of these beetle species are grain pests that do considerable damage to stored grain.You set up a dozen jars of dry meal and introduce 50 individuals of each species to each jar,being careful to have half of each species from each sex.The food supply is sufficient to last for a year and the size is adequate so that wastes do not become toxic.Most likely,examination of the jars in six months will find

Accepted Answer

The competitive exclusion principle suggests that two species competing for the same resources cannot coexist, leading to one species outcompeting the other.

Question 14

Which term describes the concept that no two species can have the same "job" in the community at the same time?

Accepted Answer

The concept that no two species can occupy the same niche (or have the same "job" in the community) at the same time is known as competitive exclusion. This principle is based on the idea that resources in a community are limited, and therefore two species competing for the same resources cannot coexist indefinitely. Eventually, one species will outcompete the other and become dominant in that niche.

Question 15

The role a species plays in the community is called its

Accepted Answer

The ecological niche refers to the role a species plays in its community, including its interactions with other organisms and its use of resources. A habitat refers to the physical environment where a species resides, while biotic and abiotic roles are not commonly used terms in ecology. Ecology is the study of the relationships between organisms and their environment, but is not specifically related to the role of a species in a community.

Question 16

Interaction between two species as both attempt to use the same environmental resources is

Accepted Answer

When two species attempt to use the same resources, they are engaging in competition. This can occur between individuals of the same or different species, and is a common feature of most ecosystems.

Question 17

Which of the following human populations would be expected to have the greatest increase in growth rate?

Accepted Answer

A population with most of its population under the age of 18 years of age would be expected to have the greatest increase in growth rate because these individuals are still in their reproductive years and are likely to have more children, leading to an increase in the population.

Question 18

Interaction between two species in which one feeds on the other is

Accepted Answer

Predation is the interaction between two species in which one species, called the predator, feeds on the other species, called the prey.

Question 19

In an Asian rice paddy,carp eat decaying material from around the base of rice plants while a snail scrapes algae from the leaves,stems,and roots of the same plant.They can survive at the same time in the same rice paddy because they

Accepted Answer

The carp and snail occupy the same habitat, i.e., the Asian rice paddy, but they use different resources. The carp eat decaying material from around the base of rice plants while the snail feeds on algae from the leaves, stems, and roots of the same plants. Therefore, they can coexist in the same habitat without competing for the same resources.

Question 20

Replacement reproduction cannot bring about zero population growth unless

Accepted Answer

Replacement reproduction refers to the idea that each couple replaces themselves with two offspring, leading to a stable population size. For zero population growth to occur, each generation must only replace themselves, meaning that the number of older women leaving reproductive years is equal to the number of younger women entering reproductive years. Therefore, choice C is the correct answer. Choices A, B, D, and E may affect population growth, but they do not specifically address the condition for zero population growth.

Quiz 34: Population Ecology